Method for increasing crude oil production by co2 storage in aquifer and dumpflooding

Abstract

A method of increasing crude oil production by CO2 storage in an aquifer and dumpflooding includes the following steps. Wells are drilled in an aquifer in an oil-bearing basin for large-scale CO2 storage. A low-production and low-efficiency well in an oil-bearing stratum away from the CO2 storage injection well is selected as an artesian injection well. Formation water in the aquifer with increasing pressure is controlled and guided into the oil-bearing stratum to realize oil displacement by dumpflooding in the oil-bearing stratum.

What is claimed is: 
     
         1 . A method of increasing crude oil production by CO 2  storage in an aquifer and dumpflooding, comprising:
 (1) selecting an aquifer within a regional unit of an oil-bearing basin; drilling at least one CO 2  injection well in a structural high part of the aquifer, wherein a perforation position of each of the at least one CO 2  injection well is located at a middle-lower part of the aquifer; and within the regional unit of the oil-bearing basin, selecting a deep aquifer with a burial depth of greater than 800 m and a formation water salinity exceeding 3 g/L;   (2) drilling at least two production wells for depletion development in the regional unit of the oil-bearing basin, wherein at least one of the at least two production wells is drilled to encounter both an oil-bearing stratum and the aquifer; and a perforation position of each of the at least two production wells is located at a middle-upper part of the oil-bearing stratum;   (3) from the at least two production wells, selecting one with a distance of 3 km or more from the at least one CO 2  injection well, and a daily oil production of less than 2 t/d or insufficient fluid supply for normal production as an artesian injection well; and perforating the artesian injection well at the middle-lower part of the aquifer, so as to communicate the aquifer with the oil-bearing stratum through a wellbore of the artesian injection well;   (4) deploying a flow-pressure detecting-controlling device in the artesian injection well, wherein the flow-pressure detecting-controlling device is located near a junction of the oil-bearing stratum and an interbedded stratum in the wellbore, and is configured to monitor and control a dump flooding rate and a flooding pressure; and deploying sequentially a first packer and a second packer in the artesian injection well, wherein the first packer is located near a top boundary of the aquifer for isolating and sealing a well section above the aquifer; and the second sealer is located near a bottom boundary of the oil-bearing stratum for isolating and sealing a well section below the oil-bearing stratum; and   (5) continuously injecting CO 2  into a geological body of the aquifer for storage through the at least one CO 2  injection well; based on an reservoir pressure accumulation effect within the aquifer during the storage of CO 2 , under the action of a pressure difference between the aquifer and the oil-bearing stratum, allowing formation water in the aquifer to flow into the wellbore of the artesian injection well and the flow-pressure detecting-controlling device; adjusting a flow rate and the flooding pressure of the flow-pressure detecting-controlling device, to make the formation water within the aquifer to flow into the oil-bearing stratum at a preset flow rate to displace crude oil to an adjacent production well for extraction.